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T - Thermoplastic vinyl, building wire, 60°C.

T Connector - A cable adapter that attaches a PC with a thinnet network interface module to the network.

T1 - The basic 24-channel 1.544 Mbps pulse code modulation system used in the United States (2.048 Mbps elsewhere). 1.544 Mbps is the old Bell System standard and 2.048 is the CCITT standard.

T1 carrier - The AT&T digital transmission system that sends data at 1.544 Mbps. With it you can simultaneously transmit 24 voice conversations, each encoded at 64,000 bits per second. More voice signals can be transmitted if you encode each conversation with fewer bits.

T3 - A digital transmission link with the capacity of 45 Mbps. Connection to the Telco is via a 4-wire or 2-wire hook-up, depending on the LEC. The equivalent of twenty-eight T1 lines or 672 56 kbps lines.

Take-up - The process of accumulating wire or cable onto a reel, bobbin or some other type of pack. Also, the device for pulling wire or cable through a piece of equipment or machine.

Tandem connection - A back-to-back connection of channel units to provide a communication path or link.

Tank test - A dielectric strength test in which the test sample is submerged in water and voltage is applied between the conductor and the water acting as ground.

Tank test - A dielectric strength test in which the test sample is submerged in water and voltage is applied between the conductor and the water acting as ground.

Tap - 1. Baseband: The component of a connector that attaches a transceiver to a cable. 2. Broadband (also called a directional tap or multi tap): A passive device used to remove a portion of the signal power from the distribution line and deliver it onto the drop line.

Taped insulation - Insulation of helically wound tapes applied over a conductor or over an assembled group of insulated conductors.

Tape wrap - A spirally applied tape over an insulated or un-insulated wire.

Taped splice - A joint with hand-applied tape insulation.

TBB - Telecommunications bonding backbone.

TBBIBC - Telecommunications bonding backbone interconnecting bonding conductor.

TC - Telecommunications closet.

TCLP - Toxicity characteristic leaching procedure. A test created by the EPA to determine whether an item can be safely discarded in an ordinary (nonhazardous) landfill.

TCP/IP (Transmission Control Protocol/Internet Protocol) - A protocol specification that conforms to the latest DoD ARPANET standard. The TCP/IP module corresponds to layers three and four of the ISO protocol model.

TDM (time division multiplexing) - A method utilizing channel capacity efficiently in which each node is allotted a small time interval, in turns, during which it may transmit a message or a portion of a message (for instance, a data packet). Nodes are given unique time slots during which they have exclusive command of the channel. The messages of many nodes are interleaved for transmission and then de-multiplexed into their proper order at the receiving end.

TDMA (time-division multiple access) - A high-speed, burst mode of operation that can be used to interconnect LANs; first used as a multiplexing technique on shared communications.

TDR - Time domain reflectometer.

Tear strength - The force required to initiate or continue a tear in a material under specified conditions.

Tearing - A picture condition in which horizontal lines are displaced in an irregular manner.

Teflon - 1.Tetrafluoroethylene 2.Trademark of the DuPont Co. for FEP, PTFE and PFA polymers.

Telco - Short for telephone company.

Telco 25- and 50-pair cable assembly - The Telco 25- and 50-pair are terminated with Amphenol157 Series or AMP Champ series connectors or other manufacturers. They are used to interconnect PABXs, controllers, modems, hubs, etc.

Telco modular cable assemblies - The twisted-pair telephone cable allows the interface of voice, video and data operation.

Telecommunications - Any transmission emission, or reception of signs, signals, writings, images and sounds, that is information of any nature by cable, radio, optical or other electromagnetic systems.

Telecommunications closet - The closet where riser cable is terminated and cross-connected to the horizontal distribution cable or other riser cable. The riser closet houses cross-connect facilities, and may contain electronics such as hubs and auxiliary power supplies for terminal equipment located at the user work location.

Telemetry - Transmission of coded analog data, often real-time parameters, from a remote site.

Tempatrure rating- The maximum temperature at which an insulating material may be used in continuous operation without loss of its basic properties.

Tensile strength - The maximum load per unit of original cross-sectional area that a conductor attains when tested in tension to rupture.

Terminal - Any device capable of sending or receiving data over a data communications channel.

Terminal alarms - Alarm indications at the transmission terminals such as a D4 channel bank.

Terminal block - A protected or unprotected unit of wiring blocks and troughs that serves as a transition point between cable conductors.

Terminal server - 1. A device which controls communication between terminals and hosts, thus off-loading hosts of this function. 2. In LAN technology, a device that allows one or more terminals or other devices to connect to an Ethernet LAN.

Terminals - Metal wire termination devices designed to handle one or more conductors, and to be attached to a board, bus or block with mechanical fasteners.

Termination - A generic term meaning the point at the end of a cable run where the cable’s conductors are attached to a termination connection such as a connector, plug, block or patch panel. Also a noninductive resistor that has the same resistance as the characteristic of the cable being used.

Termination point - The ending point of a circuit.

Terminator - A resistive device used to terminate the end of a cable or an unused tap into its characteristic impedance. The terminator prevents interference-causing signal reflections.

Test lead - A flexible, insulated lead wire used for making tests, connecting instruments to a circuit temporarily, or for making temporary electrical connections.

Tew - Canadian Standards Association type appliance wires. Solid or stranded single conductor, plastic-insulated, 105°C, 600 V TFE.

Textile braid - Any braid made from threads of cotton, silk or synthetic fibers.

TF - A UL cable type. Fixture wire, thermoplastic-covered solid or seven strands, 60°C.

TFE - One of three types of Teflon. Also known as PTFE (polytetrafluoroethylene).

TFF - Same as TF but flexible stranding, 60°C.

TFFN - Same as TFF but with nylon outer jacket.

TFN - Same as TF but with nylon outer jacket.

TG - Flexible nickel or nickel-clad copper conductor, Teflon tape, glass braid, 200°C.

TGB - Telecommunications grounding busbar.

TGGT - PTFE Teflon tape insulation with an insulation covering of wrapped glass yarn and an overall sheath of braided glass yarn impregnated with a moisture, heat, flame and fraying resistant compound. 600 V, 250°C appliance wire.

TGS - Solid or flexible copper, nickel-clad iron or copper, or nickel conductor. Teflon tape, silicone glass braid, 600 V 250°C.

Thermal aging - Exposure to a thermal condition or programmed series of conditions for pre-described periods of time.

Thermal shock - Taking an electronic device from an elevated ambient temperature where it has stabilized and immersing it in a severely cold environment, so cooling of the device is extremely rapid.

Thermocouple - A device consisting of two dissimilar metals in physical contact, which when heated will develop an EMF output.

Thermocouple element - A thermocouple designed to be used as part of an assembly, but without associated parts such as terminal block, connecting head or protecting tube.

Thermocouple extension cable - A cable comprised of one or more twisted thermocouple extension wires under a common sheath.

Thermocouple extension wire - A pair of wires of dissimilar alloys having EMF temperature characteristics complementing the thermocouple with which it is intended to be used, such that when properly connected allows the EMF to be accurately transmitted to the reference junction.

Thermocouple lead wire - An insulated pair of wires used from the thermocouple to a junction box.

Thermoplastic - A plastic material that softens and flows when heated and becomes firm when cooled. This process can be repeated.

Thermoset - A plastic material that is cross linked by a heating process known as curing. Once cured, thermoset cannot be reshaped.

THHN (thermoplastic high-heat resistant nylon coated) - THHN conductors are primarily used for power and control circuits in commercial and industrial applications. THHN meets or exceeds UL Standard 83; conductors rated for 600 V, 90°C operation in dry locations. Product is oil, gasoline and abrasion resistant. It is the common electrical wire that electricians pull in conduit.

Thick Ethernet (Thicknet) - In LAN technology, an Ethernet LAN or IEEE 802.3 LAN that uses a bus topology. Also known as 10BASE5.

Thin Ethernet - In LAN technology, an Ethernet LAN or IEEE 802.3 LAN that uses smaller-than-normal diameter coax often used to link IBM personal computers together. Operates at same frequency as Ethernet but at smaller distances. Also known informally as cheapernet.

Thinwire - A variant of 10 Mbps Ethernet that uses thin coaxial cable (RG-58 or similar, as opposed to the thicker RG-8 cable used in 10BASE5 networks) terminated with BNC connectors.

Three-phase current - Current delivered through three wires, with each wire serving as a return for the other two.

Three-phase three-wire system - An alternating current supply system comprising three conductors over which three-phase power is sent.

Three-quarter-hard wire - As applied to aluminum, wire that has been processed to produce a strength approximately midway between that of half-hard wire and that of hard-drawn wire.

Three-wire system - A DC or single-phase AC system comprising three conductors, one of which is maintained at a potential midway between the potential of the other two.

Throughput - The total useful information processed or communicated during a specified time period. Expressed in bits per second or packets per second.

THW - A UL cable type. Thermoplastic vinyl-insulated building wire. Flame-retardant, moisture and heat resistant. 75°C rated in dry and wet locations.

THW-2 - A UL cable type. Thermoplastic vinyl-insulated building wire. Flameretardant, moisture and heat resistant. 90°C rated in dry and wet locations.

THWN (thermoplastic heat- and water-resistant nylon coated) - A UL cable type. Same as THW but with nylon jacket overall. THWN conductors are primarily used for power and control circuits in commercial and industrial applications. THWN meets or exceeds UL Standard 83; conductors rated for 600 V; 90°C operation in dry locations and 75°C in wet locations. Product is oil, gasoline and abrasion resistant.

THWN-2 - A UL cable type. Same as THW but with nylon jacket overall. Rated 90°C in wet and dry locations.

TIA - Telecommunications Industry Association.

TIA/EIA-568 Commercial Building Telecommunications Cabling Standard - The U.S. standard that specifies:

  • Minimum requirements for telecommunications cabling within an office environment
  • Recommended topology and distances
  • Media by parameters that determine performance
  • Connectors and pin assignments to ensure interconnectivity
  • The useful life of telecommunications cabling systems to be in excess of ten years

Timebase corrector (TBC) - An electronic circuit that aligns unsynchronized video signals before signal processing. Used in multiplexers and quad splatters.

Timing pulses - Pulses used for synchronizing the transceiver circuits of a transmission facility. They can be generated from a local, loop or external source.

Tinned wire - See COATED WIRE.

Tin overcoat (TOC) - Tinned copper wire, stranded, then coated with tin.

Tinsel wire - A low-voltage stranded wire, with each strand a very thin conductor ribbon spirally wrapped around a textile yarn.

Tip - One of the two wires in a telephone circuit. The tip wire usually has a positive battery potential relative to the ring wire.

TKGT - PTFE Teflon tape insulation with an insulating covering of felted K-fiber yarn and an overall sheath of braided glass yarn impregnated with a moisture-, heat-, flame- and fraying-resistant compound. 250°C 600 V apparatus and motor lead wire.

TL-9000 - A quality system for the telecommunications industry based on ISO 9000.

TMGB - Telecommunications main grounding busbar.

TNC - A threaded connector for miniature coax; TNC is said to be an abbreviation for threaded-NeillConcelman. Contrast with BNC.

Token bus - A LAN access mechanism and topology in which all stations actively attached to the bus listen for a broadcast token or supervisory frame; stations wishing to transmit must receive the token before doing so. However, the next logical station to receive the token is not necessarily the next physical station on the bus. Bus access is controlled by pre-assigned priority algorithms.

Token passing - A mechanism whereby each device receives and passes the right to use the channel. Tokens are special bit patterns or packets usually several bits in length that circulate from node to node when there is no message traffic. Possession of the token gives a node exclusive access to the network for transmitting its message.

Token ring - The token access procedure used on a network with sequential or ring topology; passes tokens from adapter to adapter.

TOP (technical office protocol) - An OSI profile designed for the technical and office LAN environment.

Topcoated - Bare (untinned) copper wire, stranded then coated with pure tin.

Topology - 1. Physical topology; the configuration of network nodes and links. Description of the physical geometric arrangement of the links and nodes that make up a network, as determined by their physical connections. 2. Logical topology; description of the possible logical connections between network nodes, indicating which pairs of nodes are able to communicate, whether or not they have a direct physical connection. Examples of network topologies are as follows:

  • Bus
  • Ring
  • Star
  • Tree

TP-MAU (twisted-pair medium access unit) - DSI’s MAU that provides conversion from an AUI connector to a 10BASE-T RJ45 connector.

TP-PMD - Twisted-pair physical layer medium dependent.

TPE - Thermoplastic elastomer.

Tracer - A means of identifying an individual conductor (e.g., for polarity, etc.).

Tracking - A zoom lens’s ability to remain in focus during the entire zoom range from wide angle to telephoto position.

Transceiver - A device required in baseband networks that takes the digital signal from a computer or terminal and imposes it on the baseband medium.

Transceiver cable - Cable connecting the transceiver to the network interface controller allowing nodes to be placed away from the baseband medium.

Transceiver drop cable - A cable used to attach a drop device to a standard Ethernet segment.

Transceiver tap - The transceiver mounting mechanism that allows transceivers to be installed on a network without interrupting network operation.

Transducer - Any device that senses one form of energy and converts it to another, as sound, force, temperature or humidity to electrical energy, or vice versa.

Transfer impedance - The ratio of the source voltage of the wires inside the cable to the shield current of a cable or connectorized cable assembly.

Transfer impedance test - A laboratory test that measures the effectiveness of a cable shield to keep EMI in (or out) of the cable. Usually conducted per NEMA WC61. Sometimes also referred to as a “surface transfer impedance” test.

Transition splice - A cable splice that connects two different types of cable.

Translation frequency - The difference between the receive and transmit frequencies.

Transition splice - A cable splice that connects two different types of cable.

Translator - An active device located at the headend that received inbound RF signals from devices connected to the network, converts them to signals at outbound frequencies and sends them back to the network in the outbound direction.

Transmission - The dispatching of a signal, message, or other form of intelligence by wire, radio, telegraphy, telephony, facsimile, or other means.

Transmission cable - Two or more transmission lines. See TRANSMISSION LINE.

Transmission line - The conductors used to carry electrical energy from one location to another.

Transmission loss - The decrease or loss in power during transmission of energy from one point to another. Usually expressed in decibels.

Transmission media - The various types of wire and optical fiber cable used for transmitting voice, data or video signals.

Transmission medium - A physical carrier of electrical energy or electromagnetic radiation.

Transmitter - In a telephone it is the device in the handset that converts speech into electrical impulses for transmission.

Transposition - Interchanging the relative positions of wires to neutralize the effects of induction to or from other circuits or to minimize interference pickup by the lead-in during reception.

Tray - A cable tray system is an assembly of units or sections and ancillary fittings, made of noncombustible materials used to support cables. Cable tray systems include ladders, troughs, channels, solid bottom trays and similar structures.

Tray cable - A factory-assembled multi-conductor or multi-pair control cable approved under the National Electrical Code for installation in trays.

Treeing - Microscopic tree-like channels in medium-voltage cable insulation that can lead to cable failure.

Triaxial - A three-conductor cable with one conductor in the center, a second circular conductor concentric with and insulated from the first, and a third circular conductor insulated from and concentric with the second, and an impervious sheath overall.

Triboelectric noise - Noise generated in a shielded cable due to variations in capacitance between shielding and conductor as the cable is flexed.

Trolley wire - A round or shaped solid, bare, hard conductor ordinarily used to supply current to motors through traveling current collectors.

True concentric - A cable conductor in which each successive strand layer has a reversed direction of lay from the preceding layer.

Trunk - 1. A carrier facility (e.g., a telephone line) between two switches. 2. A telephone communications path, or channel, between two points, one of them usually being a telephone company central office or switching center. 3. The main coaxial cable which connects the headend to major segments of cable system distribution networks. Typically, a trunk cable will be used to interconnect building networks in a multi-building network.

Trunk, analog - A trunk cable that carries voice and data traffic as analog signals.

Trunk cable - A main cable used for distribution of signals over long distances throughout a cable system.

Trunk, digital - A trunk that carries voice and data traffic as digital signals.

Trunk processing - To disconnect channel units from service, so customer access is denied. This is done automatically by D4 equipment when a facility failure occurs.

TR-XLP - Tree retardant cross-linked polyethylene.

TSB (Telecommunications System Bulletin) - Additional information about an existing TIA/EIA spec. These are sometimes incorporated into later versions of the spec. A TSB is not a standard, but rather contains technical material that may be valuable to industry and users.

Tubing - A tube of extruded unsupported plastic material.

Turnkey system - Any system that is completely assembled and tested and that will be completely operational by turning it on.

TV camera cable – Multi-conductor (often composite) to carry power for camera, lights, maneuvering motors, intercom signals to operators, coaxials, etc. Usually heavy-duty jacketed.

TW - A UL wire type. Thermoplastic vinyl-jacketed building wire, moisture resistant and rated 60°C.

Twinaxial cable - A shielded cable with two conductors that are insulated from one another and are within (and insulated from) a conductor of larger size.

Twinaxial cable assemblies (IBM) - Utilizes two coaxial systems into one connector. It is used by IBM to interface mainframes, controllers, PCs and all other compatible material.

Twin coaxial - A coaxial cable configuration containing two separate, complete coaxial cables laid parallel or twisted around each other in one unit.

Twin-lead - A transmission line having two parallel conductors separated by insulating material. Line impedance is determined by the diameter and spacing of the conductors and the insulating material and is usually 300 ohms for television receiving antennas. Also called balanced transmission line and twin-line.

Twinner - A device for twisting together two conductors.

Twinnning - Synonymous with pairing.

Twisted pair - 1. Multiple-conductor cable whose component cables are paired together twisted and enclosed within a single jacket. 2. Two insulated copper wires twisted together. The twists, or lays, are varied in length to reduce the potential for signal interference between pairs. In cables greater than 25 pairs, the twisted pairs are grouped and bound together in a common sheath. Twisted-pair cable is the most common type of transmission media.